A wire 34 cm long is to be bent in the form of a quadrilateral of maximum area in which each angle is 90°. What is the maximum area enclosed?
Define \( f(x) = \begin{cases} x^2 + bx + c, & x< 1 \\ x, & x \geq 1 \end{cases} \). If f(x) is differentiable at x=1, then b−c is equal to